Producing Dicarboxylic Acids Using Polyketide Synthases

ABSTRACT

The present invention provides for a polyketide synthase (PKS) capable of synthesizing a dicarboxylic acid (diacid). Such diacids include diketide-diacids and triketide-diacids. The invention includes recombinant nucleic acid encoding the PKS, and host cells comprising the PKS. The invention also includes methods for producing the diacids.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/040,584, filed Mar. 28, 2008, hereby incorporated byreference.

STATEMENT OF GOVERNMENTAL SUPPORT

This invention was made with government support under Contract No.DE-AC02-05CH11231 awarded by the U.S. Department of Energy. Thegovernment has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates generally to dicarboxylic acid production usingpolyketide synthases.

BACKGROUND OF THE INVENTION

Dicarboxylic acids (diacids) are important compounds that are used inthe manufacture of commercial polymers (e.g. polyesters, polyurethanes).For example, see FIG. 1. The diacid adipic acid [1] is used mainly as amonomer in the production of nylon [2], a polyamide generated throughthe reaction of [1] with hexane-1,6-diamine. Polyesters (for use infabrics and plastics of many compositions) are formed through thepolymerization of terphthalic acid [3] and a dialcohol (diol) such asethylene glycol (to make polyethylene terephalate [4]), propane diol(poly(1,3-propanediol terephthalate) [5]) or butanediol(poly(1,4-butanediolphthalate) [6]. Adipic acid is also used in thesynthesis of various polyesters.

The large scale worldwide use of nylons and polyesters requires theproduction of approximately 8 billion metric tons of [1] and 15 billionmetric tons of [3] annually. These diacids are themselves synthesizedfrom starting materials extracted from petroleum. One means of reducingthe large dependence on oil for the commercial production of polymers isto generate the diacids by a fermentation process involving the use ofpolyketide synthases.

SUMMARY OF THE INVENTION

The present invention provides for a polyketide synthase (PKS) capableof synthesizing a dicarboxylic acid (diacid). Such diacids include thediketide-diacids and triketide-diacids described in Tables 2A-F andTables 3A-KK. Such diacids can also be polyketides of more than threeketide units, such as 4, 5, or 6 or more ketide units. Such diacids canalso be polyketides of up to 8, 9 or 10 ketide units. Such diacidsincludes polyketides with functional groups comprising independently H,methyl, ethyl, hydroxyl, or carbonyl groups. In some embodiments, thediacid is a polyketide from 1, 2 or 3 to up to 4, 5, 6, 7, 8, 9, or 10ketide units.

The present invention provides for a recombinant nucleic acid thatencodes a polyketide synthase (PKS) of the present invention. Thepresent invention also provides for a vector or expression vectorcomprising a recombinant nucleic acid of the present invention. Thepresent invention provides for a host cell comprising any of therecombinant nucleic acid and/or PKS of the present invention. In someembodiments, the host cell, when cultured under a suitable condition, iscapable of producing a diacid, such as a diacid described in Tables 2A-Fand Tables 3A-KK.

The present invention provides a method of producing a diacid, such asthe diacids described in Tables 2A-F and Tables 3A-KK, comprising:providing a host cell of the present invention, and culturing said hostcell in a suitable culture medium such that the diacid is produced. Themethod can further comprise isolating said diacid from the host cell andthe culture medium. The method can further comprise reacting the diacidwith a diamine to produce a nylon. Alternatively, the method can furthercomprise reacting the diacid with a dialcohol to produce a polyester.

The present invention provides for a composition comprising a diacidisolated from a host cell from which the diacid was produced, and traceresidues and/or contaminants of the host cell.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and others will be readily appreciated by theskilled artisan from the following description of illustrativeembodiments when read in conjunction with the accompanying drawings.

FIG. 1 shows the various reactions using diacids in the manufacture ofcommercial polymers (e.g. polyesters, polyurethanes). The diacid adipicacid [1] is used mainly as a monomer in the production of nylon [2], apolyamide generated through the reaction of [1] with hexane-1,6-diamine.Polyesters are formed through the polymerization of terphthalic acid [3]and a dialcohol (diol) such as ethylene glycol (to make polyethyleneterephalate [4]), propane diol (poly(1,3-propanediol terephthalate) [5])or butanediol (poly(1,4-butanediolphthalate) [6].

FIG. 2 shows types of modules employed and corresponding precursorsutilized for incorporation into polyketide chains. Loading modules aredesignated S1 and S2. The remaining compounds represent the structuresincorporated into the growing polyketide chain employing extendermodules A-P. The dashed line indicates the C—C bond formed throughClaisen condensation; atoms to the right of the bond and the C atom atthe left of the dashed line represent the structures determined by themodule employed. The R group represents the existing acyl chain prior toincorporation determined by the module.

FIG. 3 shows a scheme for making novel polyamides or novel polyesters.

FIG. 4 shows two example of the enzymatic PKS systems use tobiosynthesize-derived diacids.

FIG. 5 shows the construction of a PKS to confirm production of adiacid. A. Loading domain and module 1 of srm PKS (Blue) is combinedwith a heterologous TE domain (black) to produce [8]. Construct in A isre-engineered to remove functional KS^(Q) domain to produce [9].Abbreviations as in FIGS. 9 and 10.

FIG. 6 shows a hybrid PKS consisting of an altered loading domain,module 1, module 2 and a TE domain to produce heotane-1,7-dioic acid.Abbreviations as in FIGS. 9 and 10.

FIG. 7 shows hybrid PKSs consisting of an altered loading domain, module1 and a TE domain to produce 2-methyl-1,5-pentanedioic acid. A. Theloading domain contains a methylmalonyl-specific AT domain (mmAT). B.The extender domain contains an mmAT domain. All other abbreviations asin FIG. 9.

FIG. 8 shows di- and tri-ketide acids to be produced from PKS constructsshowing modules required under each compound. All PKSs have alteredloading domains and extender domains as shown. Abbreviations as in FIG.9. (S) and (R) refer to the chirality of the methyl or OH groups formedfrom use of the corresponding module.

FIG. 9 shows the domain organization of the pik PKS and structures ofproposed intermediates at the end of each condensation (and reduction)cycle (3). Linear polypeptides (Pik AI-AIV) are shown as open arrows;modules are indicated; domains are shown as spheres. Color-codingindicates the segment of the nascent polyketide chain corresponds tomodule and domains employing for programming. Abbreviations: ACP, acylcarrier protein; AT, acyltransferase; DH; ER, enoylreductase; KR,β-ketoreductase; KS, β-keto acyl-ACP synthase; KS^(Q); KS domain lackingcondensation activity but maintaining decarboxylation activity; TE,thioesterase.

FIG. 10. A. Hybrid PKS composed of a loading domain containing afunctional KS^(Q) domain (blue), a single extender module (orange), anda TE domain (black), producing butyric acid. B. The same PKS as in A butlacking a functional KS^(Q) domain, producing pentanedioic acid.Abbreviations as in FIG. 9 except that mAT indicates a malonyl-specificAT domain. The color scheme is used to indicate that the loading domain,module 1, and the thiesterase domain may come from different sources

DETAILED DESCRIPTION

Before the present invention is described, it is to be understood thatthis invention is not limited to particular embodiments described, assuch may, of course, vary. It is also to be understood that theterminology used herein is for the purpose of describing particularembodiments only, and is not intended to be limiting, since the scope ofthe present invention will be limited only by the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassedwithin the invention. The upper and lower limits of these smaller rangesmay independently be included or excluded in the range, and each rangewhere either, neither or both limits are included in the smaller rangesis also encompassed within the invention, subject to any specificallyexcluded limit in the stated range. Where the stated range includes oneor both of the limits, ranges excluding either or both of those includedlimits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are now described. All publications mentioned herein areincorporated herein by reference to disclose and describe the methodsand/or materials in connection with which the publications are cited.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “and”, and “the” include plural referents unless thecontext clearly dictates otherwise. Thus, for example, reference to “adiacid” includes a plurality of such diacids, and so forth.

These and other objects, advantages, and features of the invention willbecome apparent to those persons skilled in the art upon reading thedetails of the invention as more fully described below.

Polyketide Synthases (PKS)

The present invention provides for a polyketide synthase (PKS) capableof synthesizing a diacid. Such diacids include the diketides andtriketides described in Tables 2A-F and Tables 3A-KK. Such diacids canbe polyketides of more than three ketide units, such as 4, 5, or 6 ormore ketide units. The PKS can be in a host cell, or isolated orpurified. The PKS can synthesize the diacid in vivo (in a host cell) orin vitro (in a cell extract or where all necessary chemical componentsor starting materials are provided). The present invention providesmethods of producing the diacid using any of these in vivo or in vitromeans. For example, a PKS capable of synthesizing diacid [9] comprisesmodules S1 and A (see Table 2A). For example, a PKS capable ofsynthesizing diacid [8] comprises modules S1, E and E (see Table 3A).

Polyketide synthases (PKS) employ short chain fatty acyl CoAs in Claisencondensation reactions to produce polyketides. Unlike fatty acidsynthases which utilize acetyl CoA as the starter and malonyl CoA as theextender units, and use a single module iteratively to produce thenascent acyl chains, PKSs are composed of discrete modules, eachcatalyzing the chain growth of a single step. Modules can differ fromeach other in composition so that overall, a number of differentstarters (e.g. acetyl CoA, propionyl CoA) and extenders, some of whichcontain stereospecific methyl (or ethyl) side chains can beincorporated. In addition, PKS modules do not always reduce the3-carbonyl formed from condensation but may leave it either unreduced(ketone), partially reduced (hydroxyl, 2,3-ene) or fully reduced(3-methylene). Many polyketide synthases employ malonyl CoA or[S]-2-methylmalonyl CoA as the starter for polyketide synthesis. In suchcases the terminal carboxyl group is usually removed by a decarboxylasedomain present at the N-terminus of the corresponding loading domain ofthe PKS. In summary, the structure (and chirality) of the α-carbon andβ-carbonyl is determined by the module of the PKS employed in thesynthesis of the growing chain at each particular step. Because of thecorrespondence between use of modules in the synthesis and the structureof the polyketide produced, it is possible to program the synthesis toproduce a compound of desired structure by selection and geneticmanipulation of polyketide synthases. Hence, the programming of PKSs toproduce dicarboxylic acids can be accomplished by straightforwardremoval of the N-terminal decarboxylase domain from the loading module.FIG. 2 shows the various modules and the precursor utilized by eachmodule for incorporation into the corresponding nascent acyl(polyketide) chain to give rise to the range of compounds of interest.Table 1 provides a PKS source for each module. Each PKS source iswell-known to one skilled in the art is readily available. In addition,for each module taught in Table 1, there may be other modules from otherPKS that can be used.

TABLE 1 PKS sources of the various modules. Module PKS Source S1Spiramycin PKS Loading Domain S2 Erythromycin PKS Loading Domain ARifamycin PKS Module 2 B Oligomycin PKS Module 1 C Spiramycin PKS Module1 D Pikromycin PKS Module 2 E Oligomycin PKS Module 3 F Erythromycin PKSModule 3 G Oligomycin PKS Module 5 H Primaricin PKS Module 7 I TylosinPKS Module 1 J Erythromycin PKS Module 1 K Avermectin PKS Module 7 LRapamycin PKS Module 1 M Erythromycin PKS Module 4 N Pederin Module 2 OAscomycin Module 4 P FK506 Module 4

All extender modules carry the β-acyl ACP synthase (commonly called theketosynthase or KS) domain, which conducts the decarboxylativecondensation step between the extender and the growing polyketide chain,and the acyl carrier protein (ACP) domain that carries the growing acylchain and presents it to the cognate reductive domains for reduction ofthe β-carbonyl. Modules can differ from each other in composition sothat a number of different starter and extender units, some of whichcontain stereospecific side chains (e.g. methyl, ethyl, propylene) canbe incorporated. The acyltransferase (AT) domain of each moduledetermines the extender unit (e.g. malonyl CoA, methylmalonyl CoA, etc.)incorporated. In addition, PKS modules do not always reduce theβ-carbonyl formed from condensation but may leave it either unreduced(ketone), partially reduced (hydroxyl, 2,3-ene) or fully reduced(3-methylene), as shown in FIG. 2. The ketoreductase (KR) domain reducesthe ketone to the OH function (stereospecifically); the dehydratase (DH)domain removes water from the α and β carbons leaving an α,βtrans-double bond; the enoylreductase (ER) domain reduces the doublebond to a β-methylene center; the reductive state of the β-carbonyl,therefore, is determined by the presence of functional reductive domainsin the corresponding module. Less commonly, modules are found to containan additional C-methylation domain (yielding an additional α-methyl sidechain, as in epothilone). The makeup of the PKS, therefore, determinesthe choice of starter and extender acyl units incorporated, the extentof reduction at each condensation step, and the total number of unitsadded to the chain. The wide diversity of structures of polyketides seenin nature is attributed to the diversity in PKS compositions. ThePKS-directed synthesis of the aglycone component (narbonolide) of theantibiotic pikromycin is shown in FIG. 9. The pik PKS employs 6 modules(the loading domain is at the N-terminus of module 1); the loadingdomain and modules 1, 3, 4, 5, & 6 employs the precursor[S]-2-methylmalonyl CoA, module 2 uses malonyl CoA. (Afterincorporation, however, three of the side chains are inverted through aprocess not as yet fully understood.) The various degrees of reductionafter each condensation cycle are determined by the presence of thecorresponding reduction domains in each module. The cyclic nature of theproduct of the PKS is due to the TE domain-catalyzed nucleophilic attackof the OH generated after the first condensation cycle on the terminalthioester bond at ACP6. The structure of the polyketide narbonolide,therefore, is programmed by the pik PKS.

The PKS Loading Domain and Formation of Diacids.

Though virtually all polyketides appear to start with a short chaincarboxylic acid (e.g. acetyl CoA or propionyl CoA), in reality, most ofthe polyketide synthases employ malonyl CoA or [S]-2-methylmalonyl CoAas the starter for polyketide synthesis. In such cases, as shown in FIG.9 for the pik PKS, the terminal carboxyl group at the beginning of acylchain growth is removed by a decarboxylase domain present at theN-terminus of the corresponding loading domain of the PKS, designatedKS^(Q). Termination of synthesis and release of the polyketide chainfrom the PKS normally results in the generation of a free carboxylicacid (if the acceptor of chain release is water) or, more commonly, alactone (where the acceptor is an OH group internal to the chain).Failure to remove the carboxyl group at the initiation of chain growthwould result in the generation of a diacid (if the opportunity forlactonization were prevented). This can be accomplished by removal ofthe KS^(Q) domain from the loading domain of the PKS.

An example is shown in FIG. 10, which shows a simple PKS composed of aloading domain, a single extender module capable of full reduction ofthe β-carbonyl group and a TE domain; the AT domains utilize malonyl CoAas starter and extender units. The loading domain incorporates malonylCoA but decarboxylates it leaving the two carbon acetyl-ACP moiety.Decarboxylative condensation by module 1 with a second malonyl CoA andfull reduction of the β-carbonyl group generated, followed by chainrelease generates n-butyric acid, a 4-carbon molecule. If the KS^(Q)domain of the constructed PKS were removed, the malonyl-ACP moietyproduced by the loading domain would not be decarboxylated; subsequentcondensation, reduction and chain termination would release the 5-carbondiacid, pentane-1,5-dioic acid [7]. If a second extender module capableof incorporation of malonyl CoA and full β-carbonyl reduction were addedto the KS^(Q)-deleted PKS, the resulting compound would be a 7-carbondiacid (hepatane-1,7-dioic acid). Thus, the 6-carbon straight chaindiacid (adipic acid) cannot be made by PKS engineering described here.As will be described below, however, it is possible to engineer PKSs tomake a 6-carbon branched chain (2-methylpentane) diacid.

Engineering Polyketide Synthases

The present invention provides for a recombinant nucleic acid thatencodes a polyketide synthase (PKS) of the present invention. Therecombinant nucleic acid can be a double-stranded or single-strandedDNA, or RNA. The recombinant nucleic acid can encode an open readingframe (ORF) of the PKS of the present invention. The recombinant nucleicacid can also comprise promoter sequences for transcribing the ORF in asuitable host cell. The recombinant nucleic acid can also comprisesequences sufficient for having the recombinant nucleic acid stablyreplicate in a host cell. The recombinant nucleic acid can be repliconcapable of stable maintenance in a host cell. In some embodiments, thereplicon is a plasmid. The present invention also provides for a vectoror expression vector comprising a recombinant nucleic acid of thepresent invention.

It will be apparent to one of skill in the art that a variety ofrecombinant vectors can be utilized in the practice of aspects of theinvention. As used herein, “vector” refers to polynucleotide elementsthat are used to introduce recombinant nucleic acid into cells foreither expression or replication. Selection and use of such vehicles isroutine in the art. An “expression vector” includes vectors capable ofexpressing DNAs that are operatively linked with regulatory sequences,such as promoter regions. Thus, an expression vector refers to arecombinant DNA or RNA construct, such as a plasmid, a phage,recombinant virus or other vector that, upon introduction into anappropriate host cell, results in expression of the cloned DNA.Appropriate expression vectors are well known to those of skill in theart and include those that are replicable in eukaryotic cells and/orprokaryotic cells and those that remain episomal or those that integrateinto the host cell genome.

The vectors may be chosen to contain control sequences operably linkedto the resulting coding sequences in a manner that expression of thecoding sequences may be effected in an appropriate host. Suitablecontrol sequences include those that function in eukaryotic andprokaryotic host cells. If the cloning vectors employed to obtain PKSgenes encoding derived PKS lack control sequences for expressionoperably linked to the encoding nucleotide sequences, the nucleotidesequences are inserted into appropriate expression vectors. This can bedone individually, or using a pool of isolated encoding nucleotidesequences, which can be inserted into host vectors, the resultingvectors transformed or transfected into host cells, and the resultingcells plated out into individual colonies. Suitable control sequencesfor single cell cultures of various types of organisms are well known inthe art. Control systems for expression in yeast are widely availableand are routinely used. Control elements include promoters, optionallycontaining operator sequences, and other elements depending on thenature of the host, such as ribosome binding sites. Particularly usefulpromoters for prokaryotic hosts include those from PKS gene clustersthat result in the production of polyketides as secondary metabolites,including those from Type I or aromatic (Type II) PKS gene clusters.Examples are act promoters, tcm promoters, spiramycin promoters, and thelike. However, other bacterial promoters, such as those derived fromsugar metabolizing enzymes, such as galactose, lactose (lac) andmaltose, are also useful. Additional examples include promoters derivedfrom biosynthetic enzymes such as for tryptophan (trp), the β-lactamase(bla), bacteriophage lambda PL, and T5. In addition, syntheticpromoters, such as the tac promoter (U.S. Pat. No. 4,551,433; herebyincorporated by reference), can be used.

As noted, particularly useful control sequences are those whichthemselves, or with suitable regulatory systems, activate expressionduring transition from growth to stationary phase in the vegetativemycelium. Illustrative control sequences, vectors, and host cells ofthese types include the modified S. coelicolor CH999 and vectorsdescribed in PCT publication no. WO 96/40968 and similar strains of S.lividans. See U.S. Pat. Nos. 5,672,491; 5,830,750; 5,843,718; and6,177,262, each of which is hereby incorporated by reference. Otherregulatory sequences may also be desirable which allow for regulation ofexpression of the PKS sequences relative to the growth of the host cell.Regulatory sequences are known to those of skill in the art, andexamples include those which cause the expression of a gene to be turnedon or off in response to a chemical or physical stimulus, including thepresence of a regulatory compound. Other types of regulatory elementsmay also be present in the vector, for example, enhancer sequences.

Selectable markers can also be included in the recombinant expressionvectors. A variety of markers are known which are useful in selectingfor transformed cell lines and generally comprise a gene whoseexpression confers a selectable phenotype on transformed cells when thecells are grown in an appropriate selective medium. Such markersinclude, for example, genes that confer antibiotic resistance orsensitivity to the plasmid.

The various PKS nucleotide sequences, or a mixture of such sequences,can be cloned into one or more recombinant vectors as individualcassettes, with separate control elements or under the control of asingle promoter. The PKS subunits or components can include flankingrestriction sites to allow for the easy deletion and insertion of otherPKS subunits. The design of such restriction sites is known to those ofskill in the art and can be accomplished using the techniques describedabove, such as site-directed mutagenesis and PCR. Methods forintroducing the recombinant vectors of the present invention intosuitable hosts are known to those of skill in the art and typicallyinclude the use of CaCl₂ or other agents, such as divalent cations,lipofection, DMSO, protoplast transformation, conjugation, andelectroporation.

The present invention provides for a host cell comprising any of therecombinant nucleic acid and/or PKS of the present invention. In someembodiments, the host cell, when cultured, is capable of producing adiacid described in Tables 2A-F and Tables 3A-KK. The host cell can be aeukaryotic or a prokaryotic cell. Suitable eukaryotic cells includeyeast cells, such as from the genus Saccharomyces orSchizosaccharomyces. A suitable species from the genus Saccharomyces isSaccharomyces cerevisiae. A suitable species from the genusSchizosaccharomyces is Schizosaccharomyces pombe. Suitable prokaryoticcells include Escherichia coli or Streptomyces species.

Of the more than thirty PKSs examined, the correspondence between use ofmodules in the biosynthesis and the structure of the polyketide producedis fully understood both at the level of the protein sequence of the PKSand the DNA sequence of the corresponding genes. The programming ofmodules into polyketide structure can be identified by sequencedetermination. It is possible to clone (or synthesize) DNA sequencescorresponding to desired modules and transfer them as fully functioningunits to heterologous, otherwise non-polyketide producing hosts such asE. coli (B. A. Pfeifer, S. J. Admiraal, H. Gramajo, D. E. Cane, C.Khosla, Science 291, 1790 (2001); hereby incorporated by reference) andStreptomyces (C. M. Kao, L. Katz, C. Khosla, Science 265, 509 (1994);hereby incorporated by reference). Additional genes employed forpolyketide biosynthesis have also been identified. Genes that determinephosphopantetheine:protein transferase (PPTase) that transfer the4-phosphopantetheine co-factor of the ACP domains, commonly present inpolyketide producing hosts, have been cloned in E. coli and other hosts(K. J. Weissman, H. Hong, M. Oliynyk, A. P. Siskos, P. F. Leadlay,Chembiochem 5, 116 (2004); hereby incorporated by reference). Moreover,genes for the production of precursors such as methylmalonyl CoA andethylmalonyl CoA have also been identified and cloned in heterologoushosts. It is also possible to re-program polyketide biosynthesis toproduce a compound of desired structure by either genetic manipulationof a single PKS or by construction of a hybrid PKS composed of modulesfrom two or more sources (K. J. Weissman, H. Hong, M. Oliynyk, A. P.Siskos, P. F. Leadlay, Chembiochem 5, 116 (2004); hereby incorporated byreference). Hence, the programming of PKSs to produce diacids of desiredstructure can be accomplished by straightforward removal of theN-terminal decarboxylase domain from the loading module followed byfusion of the altered loading domain with one or more extender modulesas shown in FIG. 10.

Recombinant methods for manipulating modular PKS genes to make the PKSsof the present invention are described in U.S. Pat. Nos. 5,672,491;5,843,718; 5,830,750; 5,712,146; and 6,303,342; and in PCT publicationnos. WO 98/49315 and WO 97/02358; hereby incorporated by reference. Anumber of genetic engineering strategies have been used with variousPKSs to demonstrate that the structures of polyketides can bemanipulated to produce novel polyketides (see the patent publicationsreferenced supra and Hutchinson, 1998, Curr Opin Microbiol. 1:319-329,and Baltz, 1998, Trends Microbiol. 6:76-83; hereby incorporated byreference). In some embodiment, the components of the hybrid PKS arearranged onto polypeptides having interpolypeptide linkers that directthe assembly of the polypeptides into the functional PKS protein, suchthat it is not required that the PKS have the same arrangement ofmodules in the polypeptides as observed in natural PKSs. Suitableinterpolypeptide linkers to join polypeptides and intrapolypeptidelinkers to join modules within a polypeptide are described in PCTpublication no. WO 00/47724, hereby incorporated by reference.

The genetic constructs will employ an inactivation or deletion of theKS^(Q) domains of the loading module so that the pendent acidfunctionality will be retained. The loading domain will be fused to oneor more extender modules. The final module will be fused with athioesterase (TE) domain. For example, the loading domain (LM) from thespiramycin PKS in Streptomyces ambofaciens can be fused to module 5 ofthe nystatin (nysMod5) PKS from Streptomyces noursei and the TE domainfrom the erythromycin PKS (eryTE) from Saccharopolyspora erythraea toyield a hybrid polyketide synthase enzyme that would producepentanedioic (glutaric acid) (FIG. 4). The insertion of module 5 fromthe epothilone PKS (epoMod5) from Sorangium cellulosum between nysMod5and eryTE would yield heptanedioc acid (FIG. 4).

There is a publication that suggests that the ery TE is capable ofreleasing free acids in our system. This is an in vitro analysis, butthis property is expected to transfer to an in vivo system. Anotheroption to be considered is the use of the thioesterase MonCII from themonensin pathway in Streptomyces cinnamonensis. This enzyme has beenimplicated in the release of the linear free acid from the PKSmegasynthase.

The vast number of polyketide pathways that have been elucidated providea host of different options to produce these diacids as well as thelarge number of derivatives shown in Tables 2 and 3. While the productscan be vastly different in size and functionality, all employ virtuallythe same strategy for biosynthesis. The exact interfaces betweennon-cognate enzyme partners will be determined on a case-by-case basis.ACP-linker-KS and ACP-linker-TE regions from the proteins of interestwill be aligned to examine the least disruptive fusion point for thehybrid synthase. Genetic constructions will employ sequence and ligationindependent cloning (SLIC) so as to eliminate the incorporation ofgenetic “scarring”.

A partial list of sources of PKS sequences that can be used in makingthe PKSs of the present invention, for illustration and not limitation,includes Ambruticin (U.S. Pat. No. 7,332,576); Avermectin (U.S. Pat. No.5,252,474; MacNeil et al., 1993, Industrial Microorganisms: Basic andApplied Molecular Genetics, Baltz, Hegeman, & Skatrud, eds. (ASM), pp.245-256; MacNeil et al., 1992, Gene 115: 119-25); Candicidin (FRO008)(Hu et al., 1994, Mol. Microbiol. 14: 163-72); Epothilone (U.S. Pat. No.6,303,342); Erythromycin (WO 93/13663; U.S. Pat. No. 5,824,513; Donadioet al., 1991, Science 252:675-79; Cortes et al., 1990, Nature348:176-8); FK506 (Motamedi et al., 1998, Eur. J. Biochem. 256:528-34;Motamedi et al., 1997, Eur. J. Biochem. 244:74-80); FK520 or ascomycin(U.S. Pat. No. 6,503,737; see also Nielsen et al., 1991, Biochem.30:5789-96); Jerangolid (U.S. Pat. No. 7,285,405); Leptomycin (U.S. Pat.No. 7,288,396); Lovastatin (U.S. Pat. No. 5,744,350); Nemadectin(MacNeil et al., 1993, supra); Niddamycin (Kakavas et al., 1997, J.Bacteriol. 179:7515-22); Oleandomycin (Swan et al., 1994, Mol. Gen.Genet. 242:358-62; U.S. Pat. No. 6,388,099; Olano et al., 1998, Mol.Gen. Genet. 259:299-308); Pederin (PCT publication no. WO 2003/044186);Pikromycin (Xue et al., 2000, Gene 245:203-211); Pimaricin (PCTpublication no. WO 2000/077222); Platenolide (EP Pat. App. 791,656);Rapamycin (Schwecke et al., 1995, Proc. Natl. Acad. Sci. USA92:7839-43); Aparicio et al., 1996, Gene 169:9-16); Rifamycin (August etal., 1998, Chemistry & Biology, 5: 69-79); Soraphen (U.S. Pat. No.5,716,849; Schupp et al., 1995, J. Bacteriology 177: 3673-79);Spiramycin (U.S. Pat. No. 5,098,837); Tylosin (EP 0 791,655; Kuhstoss etal., 1996, Gene 183:231-36; U.S. Pat. No. 5,876,991). Additionalsuitable PKS coding sequences are readily available to one skilled inthe art, or remain to be discovered and characterized, but will beavailable to those of skill (e.g., by reference to GenBank). Each of thereferences cited is hereby specifically and individually incorporated byreference.

Complex polyketides comprise a large class of natural products that aresynthesized in bacteria (mainly members actinomycete family; e.g.Streptomyces), fungi and plants. Polyketides form the aglycone componentof a large number of clinically important drugs, such as antibiotics(e.g. erythromycin, tylosin), antifungal agents (e.g. nystatin),anticancer agents (e.g. epothilone), immunosuppressives (e.g.rapamycin), etc. Though these compounds do not resemble each othereither in their structure or their mode of action, they share a commonbasis for their biosynthesis, which is carried out by a group of enzymesdesignated polyketide synthases.

Diacids and Triacids Produced by PKSs

The present invention provides a method of producing a diacid, such as adiacid described in Tables 2A-F and Tables 3A-KK, comprising: providinga host cell of the present invention, and culturing said host cell in asuitable culture medium such that a diacid is produced. The method canfurther comprise isolating said diacid from the host cell and theculture medium. The method can further comprise reacting the diacid witha diamine to produce a nylon. A suitable diamine is an alkane diamine,such as hexane-1,6-diamine. Alternatively, the method can furthercomprise reacting the diacid with a dialcohol to produce a polyester. Asuitable dialcohol is an alkane diol, such as ethylene glycol, propanediol, or butanediol. A variety of methods for heterologous expression ofPKS genes and host cells suitable for expression of these genes andproduction of polyketides are described, for example, in U.S. Pat. Nos.5,843,718; 5,830,750 and 6,262,340; WO 01/31035, WO 01/27306, and WO02/068613; and U.S. Patent Application Pub. Nos. 20020192767 and20020045220; hereby incorporated by reference.

The present invention provides for a composition comprising a diacidisolated from a host cell from which the diacid was produced, and traceresidues and/or contaminants of the host cell.

Adipic acid is a six carbon chain fully reduced symmetrical aliphaticcompound with no side chains, hence no chiral centers. Only odd numberedchain length dicarboxylates can be generated by PKSs. Five-memberedchains are formed from the condensation of a starter acyl unit and twoextender acyl units. Regardless of the state of reduction of thecompound, these are designed diketides and require a loading module andone extender module for their syntheses. Seven-membered chains,triketides, are formed from the condensation of a starter and twoextender units, and employ a loading module and two extender modules.Side chains (methyl, allyl, hydroxyl) may be incorporated or formed,depending on the modules employed. Symmetric compounds with non-chiralcenters most similar in structure to adipic acid that can be produced byprogrammed PKSs are the diketide n-pentanedioic (glutaric) acid [7] andthe triketide n-heptanedoic acid [8]. These compounds are producedthrough the construction of a

polyketide synthase composed of loading module S1 and extender module E[7] or S1 and two E extender modules [8] (FIG. 2). These molecules canbe used as replacements for adipic acid or other diacids to make novelpolyamides or novel polyesters as shown in the scheme in FIG. 3. Allother diacids produced as di- and triketides by PKSs will be asymmetric.They will contain one or more double bonds or hydroxyl groups and/or oneor more methyl side chains, hence they will give rise to a mixture ofcompounds upon polymerization. Asymmetric mixtures currently havesubstantial use as low profile additives in the production of adhesivecompositions used in the manufacture of a variety of plastics.

Starting with S1 or S2, and employing any of the extender modules shownin FIG. 2 to construct PKSs, 32 diketide-diacids and 512tri-ketide-diacids can be produced. Considering stereochemistry, eachwould be chemically distinct and unique. All but compound [7] would beasymmetric. The rigidity of the backbone is enhanced by the presence ofdouble bonds and side chains. The diketides possible are shown in Tables2A-F and the triketides possible are shown in Table 3A-KK.

Tables 2A-F. Possible diketide-diacids produced from use of modulesshown in FIG. 2

TABLE 2A

Modules R₁ R₂ R₃ LM Mod1 9 H H O S1 A 10 H CH₃ O S1 F 11 H (CH₂)₃ O S1 O12 H CH₂CH₃ O S1 P 13 H H CH₂ S1 N 14 CH₃ H O S2 A 15 CH₃ CH₃ O S2 F 16CH₃ (CH₂)₃ O S2 O 17 CH₃ H CH₂ S2 N 18 CH₃ CH₂CH₃ O S2 P

TABLE 2B

Modules R₁ R₂ R₃ LM Mod1 7 H H H S1 E 19 H H OH S1 C 20 H CH₃ H S1 M 21H CH₃ OH S1 J 22 CH₃ H H S2 E 23 CH₃ H OH S2 C 24 CH₃ CH₃ H S2 M 25 CH₃CH₃ OH S2 J

TABLE 2C

Modules R₁ R₂ R₃ LM Mod1 26 H H OH S1 B 27 H CH₃ OH S1 I 28 CH₃ H OH S2B 30 CH₃ CH₃ OH S2 I

TABLE 2D

Modules R₁ R₂ R₃ LM Mod1 31 H CH₃ H S1 L 32 H CH₃ OH S1 H 33 CH₃ CH₃ HS2 L 34 CH₃ CH₃ OH S2 H

TABLE 2E

Modules R₁ R₂ R₃ LM Mod1 35 H CH₃ OH S1 G 36 CH₃ CH₃ OH S2 G

TABLE 2F

Modules R₁ R₂ LM Mod1 37 H H S1 D 38 H CH₃ S1 K 39 CH₃ H S2 D 40 CH₃ CH₃S2 K

Tables 3A-KK. Possible triketide-diacids produced from use of modulesshown in FIG. 2.

TABLE 3A

Modules R₁ R₂ R₃ R₄ R₅ LM Mod1 Mod2 8 H H H H H S1 E E 41 H H H OH H S1E C 42 H H H H OH S1 C E 43 H H H OH OH S1 C C 44 H H CH₃ H H S1 E M 45H H CH₃ OH H S1 E J 46 H H CH₃ H OH S1 C M 47 H H CH₃ OH OH S1 C J 48 HCH₃ H H H S1 M E 49 H CH₃ H OH H S1 M C 50 H CH₃ H H OH S1 J E 51 H CH₃H OH OH S1 J C 52 H CH₃ CH₃ H H S1 M M 53 H CH₃ CH₃ OH H S1 M J 54 H CH₃CH₃ H OH S1 J M 55 H CH₃ CH₃ OH OH S1 J J 56 CH₃ H H H H S2 E E 57 CH₃ HH OH H S2 E C 58 CH₃ H H H OH S2 C E 59 CH₃ H H OH OH S2 C C 60 CH₃ HCH₃ H H S2 E M 61 CH₃ H CH₃ OH H S2 E J 62 CH₃ H CH₃ H OH S2 M C 63 CH₃H CH₃ OH OH S2 C J 64 CH₃ CH₃ H H H S2 M E 65 CH₃ CH₃ H OH H S2 M C 66CH₃ CH₃ H H OH S2 J E 67 CH₃ CH₃ H OH OH S2 J C 68 CH₃ CH₃ CH₃ H H S2 MM 69 CH₃ CH₃ CH₃ OH H S2 M J 70 CH₃ CH₃ CH₃ H OH S2 J M 71 CH₃ CH₃ CH₃OH OH S2 J J

TABLE 3C

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 88 H H H H S1 B E 89 H H CH₃ H S1 B M90 H H H OH S1 B C 91 H H CH₃ OH S1 B J 92 H CH₃ H H S1 I E 93 H CH₃ CH₃H S1 I M 94 H CH₃ H OH S1 I C 95 H CH₃ CH₃ OH S1 I J 96 CH₃ H H H S2 B E97 CH₃ H CH₃ H S2 B M 98 CH₃ H H OH S2 B C 99 CH₃ H CH₃ OH S2 B J 100CH₃ CH₃ H H S2 I E 101 CH₃ CH₃ CH₃ H S2 I M 102 CH₃ CH₃ H OH S2 I C 103CH₃ CH₃ CH₃ OH S2 I J

TABLE 3B

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 72 H H H H S1 E B 73 H H CH₃ H S1 E I74 H CH₃ H H S1 M B 75 H CH₃ CH₃ H S1 M I 76 H H H OH S1 C B 77 H H CH₃OH S1 C I 78 H CH₃ H OH S1 J B 79 H CH₃ CH₃ OH S1 J I 80 CH₃ H H H S2 EB 81 CH₃ H CH₃ H S2 E I 82 CH₃ CH₃ H H S2 M B 83 CH₃ CH₃ CH₃ H S2 M I 84CH₃ H H OH S2 C B 85 CH₃ H CH₃ OH S2 C I 86 CH₃ CH₃ H OH S2 J B 87 CH₃CH₃ CH₃ OH S2 J I

TABLE 3D

Modules R₁ R₂ R₃ LM Mod1 Mod2 104 H H H S1 B B 105 H H CH₃ S1 B I 106 HCH₃ H S1 I B 107 H CH₃ CH₃ S1 I I 108 CH₃ H H S2 B B 109 CH₃ H CH₃ S2 BI 110 CH₃ CH₃ H S2 I B 111 CH₃ CH₃ CH₃ S2 I I

TABLE 3E

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 112 H H H H S1 L E 113 H H OH H S1 L C114 H CH₃ H H S1 L M 115 H CH₃ OH H S1 L J 116 H H H OH S1 H E 117 H HOH OH S1 H C 118 H CH₃ H OH S1 H M 119 H CH₃ OH OH S1 H J 120 CH₃ H H HS2 L E 121 CH₃ H OH H S2 L C 122 CH₃ CH₃ H H S2 L M 123 CH₃ CH₃ OH H S2L J 124 CH₃ H H OH S2 H E 125 CH₃ H OH OH S2 H C 126 CH₃ CH₃ H OH S2 H M127 CH₃ CH₃ OH OH S2 H J

TABLE 3H

Modules R₁ R₂ R₃ LM Mod1 Mod2 152 H H H S1 E G 153 H H OH S1 C G 154 HCH₃ H S1 M G 155 H CH₃ OH S1 J G 156 CH₃ H H S2 E G 157 CH₃ H OH S2 C G158 CH₃ CH₃ H S2 M G 159 CH₃ CH₃ OH S2 J G

TABLE 3F

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 128 H H H H S1 E L 129 H H OH H S1 E H130 H H H OH S1 C L 131 H H OH OH S1 C H 132 H CH₃ H H S1 M L 133 H CH₃OH H S1 M H 134 H CH₃ H OH S1 J L 135 H CH₃ OH OH S1 J H 136 CH₃ H H HS2 E L 137 CH₃ H OH H S2 E H 138 CH₃ H H OH S2 C L 139 CH₃ H OH OH S2 CH 140 CH₃ CH₃ H H S2 M L 141 CH₃ CH₃ OH H S2 M H 142 CH₃ CH₃ H OH S2 J L143 CH₃ CH₃ OH OH S2 J H

TABLE 3I

Modules R₁ R₂ R₃ LM Mod1 Mod2 160 H H H S1 B L 161 H H OH S1 B H 162 HCH₃ H S1 I L 163 H CH₃ OH S1 I H 164 CH₃ H H S2 B L 165 CH₃ H OH S2 B H166 CH₃ CH₃ H S2 I L 167 CH₃ CH₃ OH S2 I H

TABLE 3J

Modules R₁ R₂ LM Mod1 Mod2 168 H H S1 B G 169 H CH₃ S1 I G 170 CH₃ H S2B G 171 CH₃ CH₃ S2 I G

TABLE 3G

Modules R₁ R₂ R₃ LM Mod1 Mod2 144 H H H S1 L L 145 H OH H S1 L H 146 H HOH S1 H L 147 H OH OH S1 H H 148 CH₃ H H S2 L L 149 CH₃ OH H S2 L H 150CH₃ H OH S2 H L 151 CH₃ OH OH S2 H H

TABLE 3K

Modules R₁ R₂ R₃ LM Mod1 Mod2 172 H H H S1 L B 173 H CH₃ H S1 L I 174 HH OH S1 H B 175 H CH₃ OH S1 H I 176 CH₃ H H S2 L B 177 CH₃ CH₃ H S2 L I178 CH₃ H OH S2 H B 179 CH₃ CH₃ OH S2 H I

TABLE 3L

Modules R₁ R₂ R₃ LM Mod1 Mod2 180 H H H S1 G E 181 H H OH S1 G C 182 HCH₃ H S1 G M 183 H CH₃ OH S1 G J 184 CH₃ H H S2 G E 185 CH₃ H OH S2 G C186 CH₃ CH₃ H S2 G M 187 CH₃ CH₃ OH S2 G J

TABLE 3P

Modules R LM Mod1 Mod2 200 H S1 G G 201 CH₃ S2 G G

TABLE 3M

Modules R₁ R₂ LM Mod1 Mod2 188 H H S1 G B 189 H CH₃ S1 G 1 190 CH₃ H S2G B 191 CH₃ CH₃ S2 G I

TABLE 3Q

Modules R₁ R₂ R₃ R₄ R₅ LM Mod1 Mod2 202 H H H O H S1 E A 203 H H H O OHS1 C A 204 H H CH₃ O H S1 E F 205 H H CH₃ O OH S1 C F 206 H H (CH₂)₃ O HS1 E O 207 H H (CH₂)₃ O OH S1 C O 208 H H CH₂CH₃ O H S1 E P 209 H HCH₂CH₃ O OH S1 C P 210 H CH₃ H O H S1 M A 211 H CH₃ H O OH S1 J A 212 HCH₃ CH₃ O H S1 M F 213 H CH₃ CH₃ O OH S1 J F 214 H CH₃ (CH₂)₃ O H S1 M O215 H CH₃ (CH₂)₃ O OH S1 J O 216 H CH₃ CH₂CH₃ O H S1 M P 217 H CH₃CH₂CH₃ O OH S1 J P 218 H H H CH₂ H S1 E N 219 H H H CH₂ OH S1 C N 220 HCH₃ H CH₂ H S1 M N 221 H CH₃ H CH₂ OH S1 J N 222 H H H O H S2 E A 223CH₃ H H O OH S2 C A 224 CH₃ H CH₃ O H S2 E F 225 CH₃ H CH₃ O OH S2 C F226 CH₃ H (CH₂)₃ O H S2 E O 227 CH₃ H (CH₂)₃ O OH S2 C O 228 CH₃ HCH₂CH₃ O H S2 E P 229 CH₃ H CH₂CH₃ O OH S2 C P 230 CH₃ CH₃ H O H S2 M A231 CH₃ CH₃ H O OH S2 J A 232 CH₃ CH₃ CH₃ O H S2 M F 233 CH₃ CH₃ CH₃ OOH S2 J F 234 CH₃ CH₃ (CH₂)₃ O H S2 M O 236 CH₃ CH₃ (CH₂)₃ O OH S2 J O238 CH₃ CH₃ CH₂CH₃ O H S2 M P 237 CH₃ CH₃ CH₂CH₃ O OH S2 J P 238 CH₃ H HCH₂ H S2 E N 239 CH₃ H H CH₂ OH S2 C N 240 CH₃ CH₃ H CH₂ H S2 M N 241CH₃ CH₃ H CH₂ OH S2 J N

TABLE 3N

Modules R₁ R₂ LM Mod1 Mod2 192 H H S1 L G 193 H OH S1 H G 194 CH₃ H S2 LG 195 CH₃ OH S2 H G

TABLE 3O

Modules R₁ R₂ LM Mod1 Mod2 196 H H S1 G L 197 H OH S1 G H 198 CH₃ H S2 GL 199 CH₃ OH S2 G H

TABLE 3R

Modules R₁ R₂ R₃ R₄ R₅ LM Mod1 Mod2 242 H H H H O S1 A E 243 H H H OH OS1 A C 244 H H CH₃ H O S1 A M 245 H H CH₃ OH O S1 A J 248 H CH₃ H H O S1F E 247 H CH₃ H OH O S1 F C 248 H CH₃ CH₃ H O S1 F M 249 H CH₃ CH₃ OH OS1 F J 250 H (CH₂)₃ H H O S1 O E 261 H (CH₂)₃ H OH O S1 O C 252 H (CH₂)₃CH₃ H O S1 O M 253 H (CH₂)₃ CH₃ OH O S1 O J 254 H CH₂CH₃ H H O S1 P E255 H CH₂CH₃ H OH O S1 P C 256 H CH₂CH₃ CH₃ H O S1 P M 257 H CH₂CH₃ CH₃OH O S1 P J 258 H H H H CH₂ S1 N E 259 H H H OH CH₂ S1 N C 260 H H CH₃ HCH₂ S1 N M 261 H H CH₃ OH CH₂ S1 N J 262 CH₃ H H H O S2 A E 263 CH₃ H HOH O S2 A C 264 CH₃ H CH₃ H O S2 A M 285 CH₃ H CH₃ OH O S2 A J 266 CH₃CH₃ H H O S2 F E 267 CH₃ CH₃ H OH O S2 F C 268 CH₃ CH₃ CH₃ H O S2 F M269 CH₃ CH₃ CH₃ OH O S2 F J 270 CH₃ (CH₂)₃ H H O S2 O E 271 CH₃ (CH₂)₃ HOH O S2 O C 272 CH₃ (CH₂)₃ CH₃ H O S2 O M 273 CH₃ (CH₂)₃ CH₃ OH O S2 O J274 CH₃ CH₂CH₃ H H O S2 P E 275 CH₃ CH₂CH₃ H OH O S2 P C 276 CH₃ CH₂CH₃CH₃ H O S2 P M 277 CH₃ CH₂CH₃ CH₃ OH O S2 P J 278 CH₃ H H H CH₂ S2 N E279 CH₃ H H OH CH₂ S2 N C 280 CH₃ H CH₃ H CH₂ S2 N M 281 CH₃ H CH₃ OHCH₂ S2 N J

TABLE 3S

Modules R₁ R₂ R₃ R₄ R₅ LM Mod1 Mod2 282 H H H O O S1 A A 283 H H CH₃ O OS1 A F 284 H H (CH₂)₃ O O S1 A O 285 H H CH₂CH₃ O O S1 A P 286 H CH₃ H OO S1 F A 287 H CH₃ CH₃ O O S1 F F 288 H CH₃ (CH₂)₃ O O S1 F O 289 H CH₃CH₂CH₃ O O S1 F P 290 H (CH₂)₃ H O O S1 O A 291 H (CH₂)₃ CH₃ O O S1 O F292 H (CH₂)₃ (CH₂)₃ O O S1 O O 293 H (CH₂)₃ CH₂CH₃ O O S1 O P 294 HCH₂CH₃ H O O S1 P A 295 H CH₂CH₃ CH₃ O O S1 P F 296 H CH₂CH₃ (CH₂)₃ O OS1 P O 297 H CH₂CH₃ CH₂CH₃ O O S1 P P 298 H H H CH₂ O S1 A N 299 H CH₃ HCH₂ O S1 F N 300 H (CH₂)₃ H CH₂ O S1 O N 301 H CH₂CH₃ H CH₂ O S1 P N 302H H H CH₂ CH₂ S1 N N 303 H H H O CH₂ S1 N A 304 H H CH₃ O CH₂ S1 N F 305H H CH₂)₃ O CH₂ S1 N O 306 H H CH₂CH₃ O CH₂ S1 N P 307 CH₃ H H O O S2 AA 308 CH₃ H CH₃ O O S2 A F 309 CH₃ H (CH₂)₃ O O S2 A O 310 CH₃ H CH₂CH₃O O S2 A P 311 CH₃ CH₃ H O O S2 F A 312 CH₃ CH₃ CH₃ O O S2 F F 313 CH₃CH₃ (CH₂)₃ O O S2 F O 314 CH₃ CH₃ CH₂CH₃ O O S2 F P 315 CH₃ (CH₂)₃ H O OS2 O A 316 CH₃ (CH₂)₃ CH₃ O O S2 O F 317 CH₃ (CH₂)₃ (CH₂)₃ O O S2 O O318 CH₃ (CH₂)₃ CH₂CH₃ O O S2 O P 319 CH₃ CH₂CH₃ H O O S2 P A 320 CH₃CH₂CH₃ CH₃ O O S2 P F 321 CH₃ CH₂CH₃ (CH₂)₃ O O S2 P O 322 CH₃ CH₂CH₃CH₂CH₃ O O S2 P P 323 CH₃ H H CH₂ O S2 A N 324 CH₃ CH₃ H CH₂ O S2 F N325 CH₃ (CH₂)₃ H CH₂ O S2 O N 326 CH₃ CH₂CH₃ H CH₂ O S2 P N 327 CH₃ H HCH₂ CH₂ S2 N N 328 CH₃ H H O CH₂ S2 N A 329 CH₃ H CH₃ O CH₂ S2 N F 330CH₃ H (CH₂)₃ O CH₂ S2 N O 331 CH₃ H CH₂CH₃ O CH₂ S2 N P

TABLE 3T

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 332 H H H O S1 A B 333 H H CH₃ O S1 A I334 H CH₃ H O S1 F B 336 H CH₃ CH₃ O S1 F I 336 H (CH₂)₃ H O S1 O B 337H (CH₂)₃ CH₃ O S1 O I 338 H CH₂CH₃ H O S1 P B 339 H CH₂CH₃ CH₃ O S1 P I340 H H H CH₂ S1 N B 341 H H CH₃ CH₂ S1 N I 342 CH₃ H H O S2 A B 343 CH₃H CH₃ O S2 A I 344 CH₃ CH₃ H O S2 F B 345 CH₃ CH₃ CH₃ O S2 F I 346 CH₃(CH₂)₃ H O S2 O B 347 CH₃ (CH₂)₃ CH₃ O S2 O I 348 CH₃ CH₂CH₃ H O S2 P B349 CH₃ CH₂CH₃ CH₃ O S2 P I 350 CH₃ H H CH₂ S2 N B 351 CH₃ H CH₃ CH₂ S2N I

TABLE 3V

Modules R₁ R₂ R₃ LM Mod1 Mod2 372 H H O S1 A G 373 H CH₃ O S1 F G 374 H(CH₂)₃ O S1 O G 375 H CH₂CH₃ O S1 P G 376 H H CH₂ S1 N G 377 CH₃ H O S2A G 378 CH₃ CH₃ O S2 F G 379 CH₃ (CH₂)₃ O S2 O G 380 CH₃ CH₂CH₃ O S2 P G381 CH₃ H CH₂ S2 N G

TABLE 3U

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 352 H H H O S1 B A 353 H H CH₃ O S1 B F354 H H (CH₂)₃ O S1 B O 355 H H CH₂CH₃ O S1 B P 356 H H H CH₂ S1 B N 357H CH₃ H O S1 I A 358 H CH₃ CH₃ O S1 I F 359 H CH₃ (CH₂)₃ O S1 I O 360 HCH₃ CH₂CH₃ O S1 I P 351 H CH₃ H CH₂ S1 I N 362 CH₃ H H O S2 B A 363 CH₃H CH₃ O S2 B F 364 CH₃ H (CH₂)₃ O S2 B O 365 CH₃ H CH₂CH₃ O S2 B P 366CH₃ H H CH₂ S2 B N 367 CH₃ CH₃ H O S2 I A 368 CH₃ CH₃ CH₃ O S2 I F 369CH₃ CH₃ (CH₂)₃ O S2 I O 370 CH₃ CH₃ CH₂CH₃ O S2 I P 371 CH₃ CH₃ H CH₂ S2I N

TABLE 3W

Modules R₁ R₂ R₃ R₄ R₅ LM Mod1 Mod2 382 H H CH₃ H O S1 A L 383 H H CH₃OH O S1 A H 384 H H CH₃ H CH₂ S1 N L 385 H H CH₃ OH CH₂ S1 N H 386 H CH₃CH₃ H O S1 F L 387 H CH₃ CH₃ OH O S1 F H 388 H (CH₂)₃ CH₃ H O S1 O L 389H (CH₂)₃ CH₃ OH O S1 O H 390 H CH₂CH₃ CH₃ H O S1 P L 391 H CH₂CH₃ CH₃ OHO S1 P H 392 CH₃ H CH₃ H O S2 A L 393 CH₃ H CH₃ OH O S2 A H 394 CH₃ HCH₃ H CH₂ S2 N L 395 CH₃ H CH₃ OH CH₂ S2 N H 396 CH₃ CH₃ CH₃ H O S2 F L397 CH₃ CH₃ CH₃ OH O S2 F H 398 CH₃ (CH₂)₃ CH₃ H O S2 O L 399 CH₃ (CH₂)₃CH₃ OH O S2 O H 400 CH₃ CH₂CH₃ CH₃ H O S2 P L 401 CH₃ CH₂CH₃ CH₃ OH O S2P H

TABLE 3X

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 382 H H H O S1 A L 383 H H OH O S1 A H384 H H H CH₂ S1 N L 385 H H OH CH₂ S1 N H 386 H CH₃ H O S1 F L 387 HCH₃ OH O S1 F H 388 H (CH₂)₃ H O S1 O L 389 H (CH₂)₃ OH O S1 O H 390 HCH₂CH₃ H O S1 P L 391 H CH₂CH₃ OH O S1 P H 392 CH₃ H H O S2 A L 393 CH₃H OH O S2 A H 394 CH₃ H H CH₂ S2 N L 395 CH₃ H OH CH₂ S2 N H 396 CH₃ CH₃H O S2 F L 397 CH₃ CH₃ OH O S2 F H 398 CH₃ (CH₂)₃ H O S2 O L 399 CH₃(CH₂)₃ OH O S2 O H 400 CH₃ CH₂CH₃ H O S2 P L 401 CH₃ CH₂CH₃ OH O S2 P H

TABLE 3Z

Modules R₁ R₂ R₃ LM Mod1 Mod2 423 H H O S1 G A 424 H CH₃ O S1 G F 425 H(CH₂)₃ O S1 G O 426 H CH₂CH₃ O S1 G P 427 H H CH₂ S1 G N 428 CH₃ H O S2G A 429 CH₃ CH₃ O S2 G F 430 CH₃ (CH₂)₃ O S2 G O 431 CH₃ CH₂CH₃ O S2 G P432 CH₃ H CH₂ S2 G N

TABLE 3Y

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 402 H H O H S1 L A 403 H CH₃ O H S1 L F404 H (CH₂)₃ O H S1 L O 405 H CH₂CH₃ O H S1 L P 406 H H CH₂ H S1 L N 407H H O OH S1 H A 408 H CH₃ O OH S1 H F 409 H (CH₂)₃ O OH S1 H O 410 HCH₂CH₃ O OH S1 H P 411 H H CH₂ OH S1 H N 412 CH₃ H O H S2 L A 413 CH₃CH₃ O H S2 L F 414 CH₃ (CH₂)₃ O H S2 L O 415 CH₃ CH₂CH₃ O H S2 L P 416CH₃ H CH₂ H S2 L N 417 CH₃ H O OH S2 H A 418 CH₃ CH₃ O OH S2 H F 419 CH₃(CH₂)₃ O OH S2 H O 420 CH₃ CH₂CH₃ O OH S2 H P 421 CH₃ H CH₂ OH S2 H N

TABLE 3AA

Modules R₁ R₂ R₃ LM Mod1 Mod2 433 H H H S1 D D 434 H H CH₃ S1 D K 435 HCH₃ H S1 K D 436 H CH₃ CH₃ S1 K K 437 CH₃ H H S2 D D 438 CH₃ H CH₃ S2 DK 439 CH₃ CH₃ H S2 K D 440 CH₃ CH₃ CH₃ S2 K K

TABLE 3BB

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 441 H H H O S1 D A 442 H H CH₃ O S1 D F443 H H (CH₂)₃ O S1 D O 444 H H CH₂CH₃ O S1 D P 445 H OH₃ H O S1 K A 446H CH₃ CH₃ O S1 K F 447 H CH₃ (CH₂)₃ O S1 K O 448 H CH₃ CH₂CH₃ O S1 K P449 H H H CH₂ S1 D N 450 H CH₃ H CH₂ S1 K N 451 CH₃ H H O S2 D A 452 CH₃H CH₃ O S2 D F 453 CH₃ H (CH₂)₃ O S2 D O 454 CH₃ H CH₂CH₃ O S2 D P 455CH₃ CH₃ H O S2 K A 456 CH₃ CH₃ CH₃ O S2 K F 457 CH₃ CH₃ (CH₂)₃ O S2 K O458 CH₃ CH₃ CH₂CH₃ O S2 K P 459 CH₃ H H CH₂ S2 D N 460 CH₃ CH₃ H CH₂ S2K N

TABLE 3CC

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 461 H H H H S1 D E 462 H H H OH S1 D C463 H H CH₃ H S1 D M 464 H H CH₃ OH S1 D J 465 H CH₃ H H S1 K E 466 HCH₃ H OH S1 K C 467 H CH₃ CH₃ H S1 K M 468 H CH₃ CH₃ OH S1 K J 469 CH₃ HH H S2 D E 470 CH₃ H H OH S2 D C 471 CH₃ H CH₃ H S2 D M 472 CH₃ H CH₃ OHS2 D J 473 CH₃ CH₃ H H S2 K E 474 CH₃ CH₃ H OH S2 K C 475 CH₃ CH₃ CH₃ HS2 K M 476 CH₃ CH₃ CH₃ OH S2 K J

TABLE 3FF

Modules R₁ R₂ LM Mod1 Mod2 493 H H S1 D H 494 H CH₃ S1 K H 495 CH₃ H S2D H 496 CH₃ CH₃ S2 K H

TABLE 3DD

Modules R₁ R₂ R₃ LM Mod1 Mod2 477 H H H S1 D B 478 H H CH₃ S1 D I 479 HCH₃ H S1 K B 480 H CH₃ CH₃ S1 K I 481 CH₃ H H S2 D B 482 CH₃ H CH₃ S2 DI 483 CH₃ CH₃ H S2 K B 484 CH₃ CH₃ CH₃ S2 K I

TABLE 3GG

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 497 H H H H S1 E D 498 H H CH₃ H S1 E K499 H H H OH S1 C D 500 H H CH₃ OH S1 C K 501 H CH₃ H H S1 M D 502 H CH₃CH₃ H S1 M K 503 H CH₃ H OH S1 J D 504 H CH₃ CH₃ OH S1 J K 505 CH₃ H H HS2 E D 506 CH₃ H CH₃ H S2 E K 507 CH₃ H H OH S2 C D 508 CH₃ H CH₃ OH S2C K 509 CH₃ CH₃ H H S2 M D 510 CH₃ CH₃ CH₃ H S2 M K 511 CH₃ CH₃ H OH S2J D 512 CH₃ CH₃ CH₃ OH S2 J K

TABLE 3EE

Modules R₁ R₂ R₃ LM Mod1 Mod2 486 H H H S1 D L 488 H H OH S1 D G 487 HCH₃ H S1 K L 488 H CH₃ OH S1 K G 489 CH₃ H H S2 D L 490 CH₃ H OH S2 D G491 CH₃ CH₃ H S2 K L 492 CH₃ CH₃ OH S2 K G

TABLE 3HH

Modules R₁ R₂ R₃ LM Mod1 Mod2 513 H H H S1 B D 514 H H CH₃ S1 B K 515 HCH₃ H S1 I D 516 H CH₃ CH₃ S1 I K 517 CH₃ H H S2 B D 518 CH₃ H CH₃ S2 BK 519 CH₃ CH₃ H S2 I D 520 CH₃ CH₃ CH₃ S2 I K

TABLE 3II

Modules R₁ R₂ R₃ LM Mod1 Mod2 521 H H H S1 L D 522 H CH₃ H S1 L K 523 HH OH S1 G D 524 H CH₃ OH S1 G K 525 CH₃ H H S2 L D 526 CH₃ CH₃ H S2 L K527 CH₃ H OH S2 G D 528 CH₃ CH₃ OH S2 G K

TABLE 3KK

Modules R₁ R₂ R₃ R₄ LM Mod1 Mod2 533 H H H O S1 A D 534 H H CH₃ O S1 A K535 H H H CH₂ S1 N D 536 H H CH₃ CH₂ S1 N K 537 H CH₃ H O S1 F D 538 HCH₃ CH₃ O S1 F K 539 H (CH₂)₃ H O S1 O D 540 H (CH₂)₃ CH₃ O S1 O K 541 HCH,CH₃ H O S1 P D 542 H CH₂CH₃ CH₃ O S1 P K 543 CH₃ H H O S2 A D 544 CH₃H CH₃ O S2 A K 545 CH₃ H H CH₂ S2 N D 546 CH₃ H CH₃ CH₂ S2 N K 547 CH₃CH₃ H O S2 F D 548 CH₃ CH₃ CH₃ O S2 F K 549 CH₃ (CH₂)₃ H O S2 O D 550CH₃ (CH₂)₃ CH₃ O S2 O K 551 CH₃ CH₂CH₃ H O S2 P D 552 CH₃ CH₂CH₃ CH₃ OS2 P K

TABLE 3JJ

Modules R₁ R₂ LM Mod1 Mod2 529 H H S1 H D 530 H CH₃ S1 H K 531 CH₃ H S2H D 532 CH₃ CH₃ S2 H KLonger Chain Diacids from Polyketide Synthases

The polyketide backbone will increase by two carbon atoms for eachmodule employed in the biosynthesis. Employing the starter and extendermolecules shown in FIG. 2, the number of possible diacids that can beproduced by hybrid PKSs is shown in Table 4. Each class would containonly a single symmetric molecule (the fully reduced diacid); all otherswould be asymmetric

TABLE 4 Number of polyketide possible from modules shown in FIG. 2.Number Number of Number of Carbons in of General Extender PolyketidePossible Class Modules Chain Molecules Diketide 1 5 32 Triketide 2 7 512Tetraketide 3 9 8,192 Pentaketide 4 11 262,144

The invention having been described, the following examples are offeredto illustrate the subject invention by way of illustration, not by wayof limitation.

EXAMPLE 1 Production of Diacids

One can construct polyketide synthases and introduce these synthasesinto the bacterium Escherichia coli (or another readily engineered host)so that this well-known microorganism can produce from a renewable sugar(e.g., glucose) source any number of diacids that could replace thosemade from oil or other non-renewable feedstocks.

One can produce the following diacids: pentane-1,5-dioic acid;heptane-1,7-dioic acid; 2-methylpentane-1,5-dioic acid in E. coli, S.cerevisiae or Streptomyces.

The three compounds listed above require the construction of hybrid PKSscontaining two “unnatural” junctions, as well as the removal orinactivation of the KS^(Q) segment of the loading domain. A “natural”PKS can be modified to produce a diacid. The DNA segment containing theloading domain and module 1 of the spiramycin (srm) PKS is cloned intothe E. coli vector pPRO18 (S. K. Lee, J. D. Keasling, Appl EnvironMicrobiol 71, 6856 (2005); hereby incorporated by reference) or pET28Band is introduced the DNA segment containing the TE domain from the eryPKS or the monCII gene encoding a TE function from the monensinpolyketide pathway (B. M. Harvey et al., Chembiochem 7, 1435 (2006);hereby incorporated by reference) downstream of module 1 as shown inFIG. 5A. Segments are joined using SLIC (sequence and ligase independentcloning) schemes so that “scarring” (altered sequences at the junctionpoint) does not occur (M. Z. Li, S. J. Elledge, Nat Methods 4, 251(2007); hereby incorporated by reference). This construction isconfirmed correct by showing that the host (E. coli) produces(3-hydroxybutyrate) employing LCMS analysis against the authenticstandard which can be obtained commercially. The construct shown in FIG.5A is re-cloned or sub-cloned to eliminate all or most of the segmentcorresponding to the KS^(Q) domain (or use site-directed mutagenesis ofthe active site of the decarboxylation function) in the same vector asshown in FIG. 5B, and test the various constructs for production of thediacid [19], following the procedure of El-Jaber et al. (N. El-Jaber etal., J Nat Prod 66, 722 (2003); hereby incorporated by reference) forisolation and purification. The structure is confirmed by NMR analysis.Alternately, besides the production of [19] in E. coli, the construct ofFIG. 5A and the various constructs of FIG. 5B are sub-cloned intoderivatives of the Streptomyces vectors pSET152 (integrating) and pRJ446(automously replicating) and introduced them into various Streptomyceshosts (e.g. S. coelicolor, S. lividans, S. fradiae) for production of[19] in these constructs. In addition, one can use loading domain-module1 segments from other PKS systems (e.g. oligomycin, primaricin) togenerate [19] (as the 3-stereoisomer) to demonstrate the production ofthe diacid, if necessary. These approaches should yield the expecteddiacid. The PKS genes described herein, or the hosts, that carry them,are available from the American Type Culture Collection (ATCC)depository.

EXAMPLE 2 Production of pentane-1,5,-dioic acid [7]

One can follow a similar experimental pathway (as described inExample 1) to produce [7]. Because there are no natural PKS systems thatconnect a malonate utilizing-loading domain to an extender module thatcontains both a malonate-specific AT domain (mAT) and the full set ofreduction domains (DH, ER, KR) to yield a β-methylene center (FIG. 10),a “hybrid” is to be constructed. The re-constructed loading domain fromExample 1 that yields the diacid in a variety of genetic constructionsis used. These include fusion to a DNA segment containing module 5 ormodule 6 from the nystatin PKS from Streptomyces noursei ATCC 11455 ormodule 3 from the oligomycin PKS from Streptomyces avermitilis, oraddition of the DH and ER domains from a variety of modules to module 1of the srm PKS to enable full reduction to produce the required(3-methylene center. Alternatively, one can employ the segmentcontaining the loading domain through the KS domain of module 1 from asingle PKS fused to the AT-ACP segment of module 2. This keeps thecognate relationship between the loading domain ACP and the KS domain ofmodule 1, as well as maintaining the proper intermodular spacing. Athird approach is to employ the segment of the nystatin PKS encodingmodules 5 and 6 directly wherein the KS domain of module 5 is removed orinactivated enabling module 5 to serve as a loading domain. (Thepresence of the reduction domains should not interfere with its use insubsequent condensation on module 1.) Each of these constructs isattached to the TE domain as described in Example 1, placed in theappropriate vector and host and then used to test for production of [7].The PKS genes described herein, or the hosts that carry them areavailable from the ATCC depository.

EXAMPLE 3 Production of heptane-1,7-dioic acid [10]

Production of [8] requires the addition of a second extender module toproduce a triketide-diacid. To the optimal construct required to produce[7] is added an additional module containing an mAT domain and a fullset of reduction domains between module 1 and the TE domain to producethe hybrid PKS shown in FIG. 6.

EXAMPLE 4 Production of 2-methylpentane-1,5-dioic acid [11]

Two alternative strategies can be used to produce [22], as shown in FIG.7. The hybrid PKS can employ a methylmalonyl-specific AT domain (mmAT)in either the loading domain (FIG. 7A) or in the extender domain (FIG.7B). Both the loading domain and module 4 of the pik PKS (FIG. 5)contain mmAT domains (and result in the same chirality of thecorresponding methyl side chain; the [S]-2-methyl- and[S]-3-methylpentane-1,5-dioic acids are identical). Opposite chiralitycan be obtained by choice of module. In E. coli, high levels of[2S]-methylmalonyl CoA can be produced from succinyl CoA by introductionof the gene mutA from Propionibacterium shermanii (L. C. Dayem et al.,Biochemistry 41, 5193 (2002); hereby incorporated by reference). E. colistrains expressing mutA are well-known and are readily available.

EXAMPLE 5 Production of pentane-1,5-dioic acid at 1 g/l

The titers of production of [7], and its counterpart n-butyric acid [6]that employ the same basis of construction and use both constructs isdetermined. A large difference between production of n-butyric acid and[7] would suggest that either the modified loading domain does not giveoptimum utilization, or that the carboxyl group at the front end of thepolyketide inhibits flux through the PKS. The secondary structure of themRNA transcripts in the original design of the constructs is checked torule this out as a basis for poor expression. A number ofreconstructions of the loading domain can be tried to inactivate theKS^(Q) domain and look for titer increases. In addition, one canmutagenize in vitro the PKS construct of the strain that produces [7],re-introduce the DNA into the host and test several hundred independentisolates for titer increases.

If the initial evaluation does not show significant differences in thetiters of n-butyric acid and [7], the limitation of titer is due tofactors involved with the expression of the PKS DNA in the host,turnover of the PKS proteins, or the supply of substrates. One can usean ‘OMICS approach to understand the basis of the limitation (i.e.,transcript, protein and metabolite analysis). Once the limitation isdiscovered, necessary steps can be taken to remedy it (e.g. changepromoters, inactivate degradation enzymes, change hosts, eliminate sidepathways, etc.)

EXAMPLE 6 Production of Additional Diacids

Greater than one dozen extender modules that yield structural differentincorporated 2-carbon units in nascent polyketide chains are known.Variation comes from the side chain of the α-methyl carbon (H,[R]-methyl, [S]-methyl, [S]-ethyl, [S]-propylene, etc.) and the degreeof reduction of the β-carbonyl (ketone, [R]-OH, [S]-OH, ene, methylene).Employing either malonyl CoA, or methylmalonyl CoA as the starter, morethan two dozen diketide-diacids, and more than 250 triketide-diacids canbe made. One can produce 6-10 diacids or triacids employing extendermodules most readily available (e.g. where the module has been clonedpreviously and used in another application and can be re-used here).Compounds [10, 30, 37, 117, 165, 483], shown in FIG. 8, representexamples of molecules one can make and the modules required for theirconstruction. Further examples of diketide-diacids and triketide-diacidsare found taught in Tables 2A-F and Tables 3A-KK.

While the present invention has been described with reference to thespecific embodiments thereof, it should be understood by those skilledin the art that various changes may be made and equivalents may besubstituted without departing from the true spirit and scope of theinvention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processstep or steps, to the objective, spirit and scope of the presentinvention. All such modifications are intended to be within the scope ofthe claims appended hereto.

1. A polyketide synthase (PKS) capable of synthesizing a dicarboxylicacid (diacid).
 2. The PKS of claim 1, wherein the diacid comprises from1 to 10 ketide units.
 3. The PKS of claim 2, wherein the diacidcomprises from 1 to 6 ketide units.
 4. The PKS of claim 3, wherein thediacid comprises from 1 to 3 ketide units.
 5. The PKS of claim 4,wherein the diacid is one described in Tables 2A-F and Tables 3A-KK. 6.A recombinant nucleic acid that encodes a polyketide synthase (PKS) ofclaim
 1. 7. A vector or expression vector comprising the recombinantnucleic acid of claim
 6. 8. A host cell comprising the recombinantnucleic acid of claim
 6. 9. A host cell comprising the PKS of claim 1.10. A host cell comprising the vector or expression vector of claim 7.11. The host cell of claim 8, wherein the host cell is a eukaryoticcell.
 12. The host cell of claim 11, wherein the host cell is of thegenus Saccharomyces or Schizosaccharomyces.
 13. The host cell claim 8,wherein the host cell is a prokaryotic cell.
 14. The host cell of claim13, wherein the host cell is from the genus Escherichia or Streptomyces.15. A method of producing a diacid, comprising: (a) providing a hostcell of claim 8, and (b) culturing said host cell in a suitable culturemedium such that the diacid is produced.
 16. The method of claim 15,further comprising: (c) isolating said diacid from the host cell and theculture medium.
 17. The method of claim 16, further comprising: (d)reacting the diacid with a diamine to produce a nylon.
 18. The method ofclaim 16, further comprising: (d) reacting the diacid with a dialcoholto produce a polyester.
 19. A composition comprising an isolated diacidand trace residues or contaminants of the host cell using the method ofclaim 16.